Transformer and method of making the same.



I s. ATTILA.

TRANSFORMER AND METHOD OF MAKING THE SAME.

- APPLICATION FILED JULY 2 9. 1909.

1,260,743. Patented Mar. 26,1918.

5 $HEEIS-SHEET l- S. ATTILA.

TRANSFORMER AND METHOD OF MAKING THE SAME. APPLICATION FILED JULY 29. 1909.

' 13260,?43. Patented Mar. 26,1918.

5 $HEETS-SHEET 2.

S. ATTILA'; TRANSFORMER AND METHOD OF MAKING THE SAME. APPLICATION map 1uLY29. I909.

5 SHEETS-SHEET 3.

1,260,743. Patented Mar. 26, 1918.

S.. AITILA.

TRANSFORMER AND METHOD OF MAKING THE SAME.

APPLICATION \HLFD JULY 29'. mos.

PatentedMar. 26, 1918.

5 SHEETSSHEET 4.

S. ATTlLA.

TRANSFORMER AND METHOD OF MAKING THE SAME.

APPLICATION FILED 1ULY29. T909. 1 2 0,743, Patented Mar. 26,1918.

5 SHEETS-SHEET 5.

UNITED STATES PATENT OFFICE.

SULOATTILA, F FBANKFORT-ON-THE-MAIN, GERMANY, ASSIGNOR TO THE FIRM OF DEUTSCHE-ELEKTBO-SPARLICHT-GESELLSCHAFT, OF FBANKFOBT-ON-THE-MAIN,

GERMA Y,

TRANSFORMER AND METHOD OF MAKING- THE SAME.

Specification of Letters Patent. Patgnted Liar. 26, 1918.

Application at July 29, 1909. Serial No. 51 ,194.

' To all whom it may concern:

This invention relates to transformers andlike apparatus, and particularly to trans-' formers of small capacitywhich are adapted for use with metallic filament lamps.

It is well known that low voltage metallic filament lamps are not only more eflicient than high voltage lamps, but since the filament is shorter it can more easily supported and can also be made of smaller can- .dle power. Low voltage however has the objection that the line losses are excessive. If however a transformer is mounted directly at each lamp, then such objection is avoided since the line voltage can then-be relatively large while this llne voltage can be reduced at the lamp."

Where such small transformers are'used it is exceedingly diflicult to wind them if the core is in one iec'e since the holes are small. This difiiciil they are wound by hand.

One of the objects of his invention therefore is to'construct a transformer or like apparatus which" can-be easily wound and in which the magnetic joints are well made,

and another object is to provide a method of manufacturing such an apparatus.

The invention will be described in connection with the accompanying drawings, in

' which:

Figure 1 is a section on the line A-A, Fig. 2, and shows one form of transformer which is of the inclosed coil type; v Fig. 2 is a section on the line BB,' Fig. 1;

Figs. 3 to 6,-inclusive, areviews similar to Fig. 1, showing different forms of inclosed coi transformers;

Fig. 7 is a view similar, to Fig. 1, showing an open or exposed typeof transformer;

Fig. 8 is a view similar to Fig.1 showing a three-phase transformer; v

Fig. 9 is a view similar to Fig. 1 showing another form of inclosed coilitransfonner;

Figs. 10 and 11 illustrate a method and a paratus for assembling the core plates of t e type of transformer illustrated in Figs.

ty is gre'ateven where 3 to 6- inclusive "and Figs. 8 and 9; Fig. 10

.being a section on the line C-C, Fig. 11,

and Fig. 11 being a section on the line 0-0 Fig. 12 illustrates a method and-apparatus for assembling the yoke plates;

Fig. 13 shows the core with a winding thereon;

I Figs. 14 and I5 illustrate one method of winding the core;

F Fi 16 shows the type of transformer of Figs. 17 and 18 illustrate a method and apparatus for assembling the yokeplates of the form shoyvn in Figs..7 and 16, Fig. 17

beingza section on the line D-D, Fig. 18,

and ig. 18 being a section on the line E-E,

with the core and yoke partly wound;

g. 19 illustrates a method of winding 2 20 being a section on the line' F-eF,

F1 21, Fig. 21 beingFa section on the line (ii-G,

Fig. 20, and ig. 22 being a section on the.

line H-H, Fig. 20-- Fig. 23 illustrates the method "of winding the assembled core;

' Figs.- 24 and 25 illustrate the method of bringin together and a'ssemblingthe assemble core and yoke; and

show different 26 to 28 inclusive formsoftransformers which form the subject-matter of this invention and which may be made according to the method to be described.

22 illustrate a method Referring to the, drawings, and more particularlyto Figs. 1 and 2, it will be seen that the transformer there shown ,is of the inclosed coil type. The core of the transformer is made up, .as usual, of plates or laminae and .com rises a core proper des1gnated by the re erence character 1, and a yoke 2, which s'urrounds the core and the coil 3 wound thereon.

It will be readily seen that where this transformemis small, and if. both the core and the yoke are made in a single piece, that is from single stampings, it is exceedingly diflicult to place the winding on the core in view of the small space allowed. The drawings illustrate a form which shows in full size a transformer having a capacity of 40 watts and is therefore of proper size for metallic filament lamps.

Figs. 1 and 2. The core plates or laminae are stamped in the usual way and then as- 'more accurate fit.

sembled in a sleeve 4. The interior of the .sleeve corresponds to the outside contour of the core plates so that these core plates will be assembled and alined therein as will be seen from Figs. 10 and 11. After these core plates are thus alined in the sleeve they are tightly clamped'together by means of a ressure head 5 which screws into the sleeve.

he sleeve is provided with recesses 6 for the reception of clamps 7. After the plates have been assembled in the sleeve and compressed the clamps are slipped over the ends of the assembled core plates as shown in.

Figs. 10 and 11, and the assembled core may then be removed from its assembling device, the clamps holding the plates rigidly together. These clamps are preferably provided with centers so that the assembled core may be placed in a lathe or in a winding machine as shown in Figs. 14 and 15, so that the coil 3 can be wound thereon after suit able insulation has been applied to the core.

The yoke drel 9, Whic is guided-in a sleeve 8. In this case however the interior surfaces of the yoke plates are alined by the mandrel,

the internal diameter 'of the sleeve being larger than the outside diameter of the yoke plates. After the yoke plates have thus been assembled in alined relation on the mandrel and in the sleeve, they are compressed by means of a pressure head 10, as shown in Fig. 12.

The clamps 7 are now removed from the assembled and wound core since the winding and insulation thereon will be sufficient to, hold the core plates together. The assembled core is now placed in position in the head 10 and above the assembled yoke while it is still on the mandrel and in the sleeve 8, and the parts are forced together by a suitable press, the mandrel 9 receding as the core is forced ,in place, and the core being guided by the interior wall of head 10. It will be understood that the external diameter of the core is slightly greater than the internal diameter of the yoke so that the parts will be forced together, making a pressedor forced fit. .The cooperating and engagingsurfaces of the yoke and core may of course be machined in order to make a After the parts have thus been forced to ether the whole may be removed from the s eeve 8.

lates are assembled on a manby the'winding and the yoke plates will be.

held together by the core plates so that no bolts or other fastening means will be necessary. The joint between the parts will be exceedingly efficient and will have a low magnetic reluctance.

Instead of forcing the parts together b pressure the assembled yoke may be shrun on the core. This may be accomplished by heating the yoke as assembled in its sleeve (Fig. 12) until it expands sufficient to permit the assembled core to be placed therein. After the parts have been this assembled the subsequent cooling will shrink the yoke tightly on the core. which the yoke must be raised need of course not be very high since a slight' expansion and contraction is sufficient to make a good oint.

Figs. 3 to 6, inclusive, and 8 and 9 show different forms of this invention but their construction will be obvious from the illustration. It will be seen that the same these forms as to the construction shown in Fig. 1.

It is advantageous in the manufacture of apparatus of this type to stamp the core and plates out of the same material that the yoke is stamped out of. In accordance with this invention therefore the core plates may be stamped from the same material as the yoke plates and the parts can therefore be assembled and subsequently forced together. This results in a great saving of material.

Figs. 7and 16 show a transformer of the open or exposed coil type. In this case the yoke 11 and the core 12 are divided as shown so as to be of open construction, thereby permitting the parts to be wound in a lathe or other winding machine.

The core is assembled in a similar sleeve 4:, as shown in Figs. 20 to 22,,and after the plates have been compressed the clam s 7 are slipped on, these clamps being provided with centers whereby the assembled core may be placed in a lathe or other winding machine and the coil 3 Wound in place, after suitable insulation has been applied to the core. In this case also the sleeve 4 is const'ructed to engage the joint-forming surfaces of the core so as to properly aline the core plates.

The yoke is assembled in a similar manner as shown in the preceding construction and the form of mandrel 9 and sleeve 8 is shown in Figs. 17 and 18. The yoke plates are alined in the sleeve and on the mandrel as The temperature to a in the preceding method, clamped by the ment with the mandrel 9 so as to be properly placed' in assembled and alined relation, and the wound core can be forced in the assembled yoke in its sleeve, or the yoke can. .be shrunk onthe core as in the preceding.

method. It will be noted that the mandrel in this case is provided with a recess for the coil and that the clamps 7 can remain on the, core while it is being forced in place in the yoke; I

In theconstruction shown in Figs. 26 and 27 the yoke plates are made of two parts 2, 2". The separate halves of the yoke are assembled and can then be wound with wire. In this way a permanent pressure'is produced betweenthe core and yokeso as to form a good joint having a minimum magnetic reluctance. In Fig. 26 the yoke em-' braces the ends of the core, while in Fig. 27 the ends of the yoke sections abut against the lateral core faces.

If inclosed coil transformers of the kind described and illustrated in Figs. 1 to 6, "8 and 9 are to be suspended direct it ,is advisable to arrange the holes for bolts which pass through the casing or yoke plates at the point where the ma netic flux is a mini mum, that is on the axis of the core. This is shown in Fig. 28 where the bolt holes are located on the diameter 14, 14.

In manufacturing small inclosed coil transformers of the above mentioned kind it is preferable to provide the yoke plates 2 at the point at.which the winding 3 of the core plates 1 join with recesses 13, as shown in Figs. 1, 3, 4, 5,8 and 9. By means of this construction an effective stamping is obtained and the core plates can be readily made so as to have a minimum magnetic reluctance, and the parts areso constructed that the winding can be applied thereto and the parts assembled with the minimum of expense no matter how small the apparatus is.

In both press and shrinkage fits the outer member of 'the joint hugs the inner member. In a press fit the outer member isbored to a smaller diameter than the inner member and is slightly expanded by forcing the inner member into it, while in .a shrinkage fit the outer member isexpanded by heatand subsequently contracts when the parts are cooled. The opening in the laminated yoke is slightly smaller than the largest dimensions of, the core and when the two laminated parts are united they are held together as a'perman'ent unitary laminated structure solely by the mutual frictional edge engagement of the laminations of the yoke and core respectively. When the laminated yoke and laminated core are united the fibers adjacent the abutting edges will be under permanent compression in the core and underpermanent tensile stress in the Having thus described the invention, what is claimed is:

l. The herein described method of making transformers which comprises forming a series of core laminae, compressing the same together and winding a coil thereon intermediate of the ends while maintaining the laminae under compression, forming a se- 5 ries of yoke laminae and assembling the same under compression, pressing the assembled core laminae and the winding thereon into place in an opening formed in the assembled yoke laminae and transversely of the latter, whereby a permanent unitary laminated structure having a winding thereon is obtained and whereby the sole means for holding the laminated core and laminated yoke together comprises the mutual frictional edge engagement of said core laminae and yoke laminae.

2. A transformer comprising a core consisting of a series of superposed laminae compressed together, a yoke consisting of a series of superposed laminae compressed together and forming when assembled alaminated yoke having an opening therein extending transversely of the plane of the -laminae and adapted to receive the laminated core, the dimensions of said opening in the yoke being slightly smaller than the dimensions of said core whereby considerable pressure is required to force-said core into said opening and whereby the yoke and core are held together solely by mutual frictional edge engagement of the laminae comprising the core with the lamina comprising the yoke and the metal at the joint therebetween eing placed under permanent stress.

3. A small transformer for use with low voltage metallic filament lamps and equivalent translating devices and adapted to be mounted directly on a lamp setting, said transformer comprising a series of superposed core laminae compressed together, a series of superposed yoke laminae compressed together and, forming when assembled a laminated yoke having an opening therethrough slightly smaller than the largest dimension of the core and adapted to receive the laminated core, the core and yoke being held together solely by mutual frictional edge engagement of the laminae comprising the core with the laminae comprising the yoke whereby a permanent unitary laminated. structure is formed, and a Winding on the core.

4:. The method of making a laminated structure having a laminated core and a laminated yoke which comprises forming a i series of core laminae and compressing them together to provide a laminated core, forming a series of yoke laminae and compressing them together to provide a laminated of parts and including a series of superposed core laminae compressed together and forming a laminated core, a series of superposed yoke laminae compressed together and forming when assembled a laminated yoke constructed so that the core contactin surfaces thereof shall embrace the laminated core, the core and yoke being held together solely by mutual frictional edge enga ement of the laminae comprising the core w1th the laminae comprising the yoke, whereby a permanent unitary laminated structure is formed, and a Winding on one of said parts.

In testimony yvhereof I have signed my name to this specification in the presence of tWo subscribing witnesses.

sULo ATTILA.

Witnesses MICHAEL ,VOLK, ERWIN DIPPELY. 

